We don't use non-hookup campgrounds to get away from generator noise. We use them for their often superior natural beauty. Whenever other campers are using generators that tells us it's alright for us to use ours.
For battery charging, we use a small discontinued 650 watt Honda generator that runs at all of it's power output levels at a noise level just one dB above the noise level of modern Honda inverter generators when they're idling. We're believers in using as small a generator as possible for routine RV battery charging to keep both fuel consumption and noise at minimums. We use the 4KW Onan for the microwave, the air compressor, the hair dryer, the air conditioner, and - should the need ever arise - for emergency electric heating.